Answer:
6s
Explanation:
Assume it is dropped from rest and the gravitational acceleration is 10
By the equation of motion under constant acceleration:

180 = (0)t+10(t^2)/2
t = 6 or -6 (rejected)
t = 6 s
Well depending on the speed of both of those things is were the rock will be placed and it also determines how fast can an environment change
<span />
I have all the answers here so take this